<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    var num1 = +prompt('请输入第一个数字');
    var num2 = +prompt('请输入第二个数字');
    // 三元运算符
    alert(num1 > num2 ? num1 : num2);
  </script>
</body>
</html>